function A0 = one_step(A0_coef,N,M,D,B,C)
New_A0 = zeros(size(A0_coef));
for i = 1 : N
    if i == 1
        q = N;
    else
        q = i-1;
    end
    New_A0(:,i) = M\((D-B)*A0_coef(:,i) + C*A0_coef(:,q));
end
A0 = New_A0;
end